In the past, a number of patents have been granted upon processes in accordance with which suitable seals have been created between two materials that are difficult to join. The Hume U.S. Pat. No. 2,820,534 is one such teaching, and it describes how a hermetically sealed ceramic-metal structure can be created. Although such a teaching makes it possible to bond aluminum or magnesium to a ceramic, it does not represent a teaching that could sustain wide temperature variations, nor does it otherwise represent a suitable teaching for certain ceramic-metal joinders.
The Emeis U.S. Pat. No. 3,414,964 addresses the problem of producing a solder joint between metals and ceramic, involving the use of silver foil, but this process likewise falls short of providing a method that, when practiced in connection with certain non-metallic materials, enables the joint to withstand severe temperature cycling.
Likewise, the Smith U.S. Pat. No. 3,616,523 represents a method of sealing an electrically non-conductive optical window to an electrically non-conductive envelope of an electron discharge device, involving the use of an electrically conductive sealant, to which is applied heat and a high unidirectional voltage so as to effect a curing thereof. Again, however, that teaching would not permit wide temperature swings without leakage tending to occur.
It was in an effort to improve upon prior art teachings of this type that the present invention was evolved.